1. Aliases and English Name

• Chinese Alias: 沼气 (Biogas)


• English Name: Methane


• English Alias: None specified

2. Applications

Methane serves as a versatile raw material and energy source, including:

• Fuel


• Standard gas


• Calibration gas


• Production of solar cells and amorphous silicon films


• Raw material for manufacturing acetylene, hydrogen, ammonia, carbon black, methyl compounds, carbon disulfide, hydrocyanic acid, and more

3. Physical Properties

• Appearance: Methane is a colorless, odorless gas.


• Weight Ratio to Air: 0.54 (approximately half the weight of air).


• Solubility: Very low solubility in water; at 20°C and 0.1 kPa, 100 units of water dissolve 3 units of methane by volume.


• Combustion: Burns with a bright, pale blue flame.


• National Standard Code: 21007


• Melting Point: -182.5°C


• Boiling Point: -161.5°C


• Vapor Pressure: 53.32 kPa at -168.8°C


• Saturated Vapor Pressure: 53.32 kPa (-168.8°C)


• Relative Density (Water = 1): 0.42 (-164°C)


• Relative Vapor Density (Air = 1): 0.5548 (at 273.15 K and 101,325 Pa)


• Heat of Combustion: 890.31 kJ/mol


• Gross Heating Value: 55,900 kJ/kg (40,020 kJ/m³)


• Net Heating Value: 50,200 kJ/kg (35,900 kJ/m³)


• Critical Temperature: -82.6°C


• Critical Pressure: 4.59 MPa


• Explosive Limits (% V/V):
  
  • Upper Limit: 15.4%
  
  
  • Lower Limit: 5.0%
  
  


• Flash Point: -188°C


• Ignition Temperature: 538°C


• Molecular Diameter: 0.414 nm


• Density (Standard Conditions): 0.717 g/L, extremely insoluble in water [1]

4. Toxicity

• Rat Inhalation LC50: 400 ppm


• Effects on Humans: Methane itself has no specific toxic effects on the human body but can cause narcotic effects at high concentrations. High levels in the air can lead to oxygen deficiency, asphyxiation, and poisoning symptoms.
  
  • At concentrations above 10%, it may cause a sensation of pressure in the eyes and forehead.
  
  
  • At higher concentrations, symptoms include rapid breathing, fatigue, nausea, vomiting, and other signs of asphyxiation, potentially leading to loss of consciousness.
  
  


• First Aid:
  
  • Immediately move affected individuals to an uncontaminated area, ensure they rest, and keep them warm and comfortable.
  
  
  • If breathing is weak or stops, provide oxygen or perform artificial respiration immediately.
  
  
  • Seek medical attention promptly.
  
  

5. Safety Precautions

• Equipment Sealing: Equipment must be tightly sealed; leaks can be detected using soapy water. For methane, its explosiveness poses a greater risk than its toxicity.


• Material Compatibility:
  
  • Methane is non-corrosive and compatible with all common metals.
  
  
  • For liquid methane: Use iron alloys with 5%-9% nickel, austenitic steel with 37% or 9% nickel and 19% chromium, or aluminum alloys with 11% chromium and 3.9% magnesium.
  
  
  • Compatible non-metallic materials include cellulose acetate, nylon, phenol formaldehyde, phenol furan, polyethylene, polypropylene, polyurethane, polyvinyl chloride (PVC), PVC acetate, polyvinylidene chloride, polychlorotrifluoroethylene, polytetrafluoroethylene, epoxy resin, diethanol polymer, nitrile rubber, neoprene, and Hypalon.
  
  


• Firefighting: In case of fire, use water mist, foam, carbon dioxide, or preferably dry powder extinguishers.


• Leak Handling:
  
  • For leaking gas, use forced ventilation to reduce concentration below the explosive range.
  
  
  • If a leaking cylinder cannot be sealed, transfer it to an open area to vent safely or attach an appropriate burner to combust the gas.